To me, it looks like in the general way you're posing the question, that's impossible. unless the Eib387h3ox8b2 at the end of the URL encodes the "test.txt" name, but if it does, I wouldn't begin to know what decoder to use. It isn't coded in hex digits and it doesn't seem to be base64.
URLs may point to files that sit on a webserver, and these files have names on the webserver, but you can't get the the name of that file - all you have to go on is the URL. If the name isn't in the URL, in general, you're stuck. Your web server may send you the name of the file in a HTTP Header, or it might provide an API to get at the filename, but if all you have is some random URL, then no, you can't get the name of the file that is refered to by that URL.